Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F4/00—Polymerisation catalysts
  • C08F4/42—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors
  • C08F4/44—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides
  • C08F4/60—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides together with refractory metals, iron group metals, platinum group metals, manganese, rhenium technetium or compounds thereof
  • C08F4/62—Refractory metals or compounds thereof
  • C08F4/64—Titanium, zirconium, hafnium or compounds thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F10/00—Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F10/02—Ethene

Definitions

• This invention relates to a process for the polymerization of ethylene whereby an intermediate molecular weight distribution is achieved.
• Titanium and vanadium based ethylene polymerization catalysts have been known and successfully used for many years as well as mixtures of the two see e.g. US-A-4303771, EP-A-120501 and FR-A-2355562.
• the former produces resins of narrow molecular weight distribution whereas the latter, resins having broad molecular weight distribution.
• a mixed catalyst system having an intermediate molecular weight distribution in tandem with a high level of activity has, however, been elusive.
• An object of this invention is to provide a process for the polymerization of ethylene utilizing mixed titanium and vanadium based catalysts whereby a resin of intermediate molecular weight distribution is produced and the mixed catalyst system achieves a high level of activity.
• the titanium based catalyst and its method for preparation are disclosed in US-A-4303771 issued on December 1, 1981.
• the vanadium based catalyst and its method for preparation are disclosed in US-A-4508842 issued on April 2, 1985.
• the titanium compound which can be used in the above preparations, has the formula Ti(OR) a X b wherein R, OR and X are as defined for component (a)(i) above; a is 0, 1 or 2; b is 1 to 4; and a + b is 3 or 4.
• Suitable compounds are TiCl3, TiCl4, Ti(OC6H5)Cl3, Ti(OCOCH3) Cl3 and Ti (OCOC6H5)Cl3.
• the magnesium compound has the formula MgX2 wherein X is as defined for component (a)(i) above. Suitable examples are MgCl2, MgBr2, and MgI2. Anhydrous MgCl2 is a preferred compound. 0.5 to 56, and preferably 1 to 10, moles of the magnesium compound are used per mole of titanium compound.
• the electron donors used in the catalyst systems are organic compounds, liquid at temperatures in the range of 0°C to 200°C. They are also known as Lewis bases.
• the titanium, magnesium, and vanadium compounds are all soluble in the electron donor.
• Electron donors can be selected from the group consisting of alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic ketones, aliphatic amines, aliphatic alcohols, alkyl and cycloalkyl ethers, and mixtures thereof, each electron donor having 2 to 20 carbon atoms.
• these electron donors the preferred are alkyl and cycloalkyl ethers having 2 to 20 carbon atoms;
• the most preferred electron donor is tetrahydrofuran.
• suitable electron donors are methyl formate, ethyl acetate, butyl acetate, ethyl ether, dioxane, di-n-propyl ether, dibutyl ether, ethyl formate, methyl acetate, ethyl anisate, ethylene carbonate, tetrahydropyran, and ethyl propionate.
• vanadium compounds which are of interest here are vanadium trihalides wherein the halide is Cl, Br, or I, or mixtures thereof, VCl4, VOCl3, triisobutyl vanadate, and vanadium tris-acetyl acetonate.
• halide is Cl, Br, or I, or mixtures thereof
• VCl4, VOCl3, triisobutyl vanadate, and vanadium tris-acetyl acetonate are mentioned in United States patents 3,956,255 and 4,370,455.
• the modifier has the formula MX a where M is boron or AlR (3-a) ; each R is an alkyl radical having 1 to 14 carbon atoms and is alike or different; X is chlorine, bromine, or iodine; and a is 0, 1, or 2 except that, when M is boron, a is 3.
• Preferred modifiers include alkylaluminum mono- and di-chlorides wherein each alkyl radical has 1 to 6 carbon atoms, and boron trichloride.
• a particularly preferred modifier is diethyl aluminum chloride. 0.1 to 10 moles, and preferably 0.2 to 2.5 moles, of modifier are used per mole of electron donor. When the modifier is used it is considered to be part of the titanium and/or vanadium complex.
• the hydrocarbyl aluminum cocatalyst can be represented by the formula R3Al wherein each R is an alkyl, cycloalkyl, aryl, or hydride radical; at least one R is a hydrocarbyl radical; two or three R radicals can be joined in a cyclic radical forming a heterocyclic structure; each R can be alike or different; and each R, which is a hydrocarbyl radical, has 1 to 20 carbon atoms, and preferably 1 to 10 carbon atoms.
• each alkyl radical can be straight or branched chain and such hydrocarbyl radical can be a mixed radical, i.e., the radical can contain alkyl, aryl and/or cycloalkyl groups.
• radicals are: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, 2-methylpentyl, heptyl, octyl, isooctyl, 2-ethylhexyl, 5,5-dimethylhexyl, nonyl, decyl, isodecyl, undecyl, dodecyl, phenyl, phenethyl, methyloxyphenyl, benzyl, tolyl, xylyl, naphthyl, naphthal, methylnaphthyl, cyclohexyl, cycloheptyl, and cyclooctyl.
• hydrocarbyl aluminum compounds are as follows: triisobutylaluminum, trihexylaluminum, di-isobutylaluminum hydride, dihexylaluminum hydride, isobutylaluminum dihydride, hexylaluminum dihydride, di-isobutylhexylaluminum, isobutyl dihexylaluminum, trimethylaluminum, triethylaluminum, tripropylaluminum, triisopropylaluminum, tri-n-butylaluminum, trioctylaluminum, tridecylaluminum, tridodecylaluminum, tribenzylaluminum, triphenylaluminum, trinaphthylaluminum, and tritolylaluminum.
• the preferred hydrocarbyl aluminums are triethylaluminum, triisobutylaluminum, trihexylaluminum, di-isobutylaluminum hydride, and dihexylaluminum hydride.
• the halocarbon promoter can have the following formula: R x CX (4-x) wherein R is hydrogen or an unsubstituted or halo substituted alkyl radical having 1 to 6 carbon atoms; each R is alike or different; X is Cl, Br, I, or F; each X is alike or different; and x is 0, 1, or 2 provided that, if no F is present, x is 2.
• Suitable promoters are CH2Cl2, CFCl3, CH2BrCl, and ClCF2CCl3; of which difluorotetrachloroethane and methylene dichloride are preferred.
• Silica is the preferred support.
• suitable inorganic oxides are aluminum phosphate, alumina, silica/alumina mixtures, silica modified with an organoaluminum compound such as triethylaluminum, and silica modified with diethylzinc.
• a typical support is a solid, particulate porous material essentially inert to the polymerization.
• the amount of support used is that which will provide 0.05 to 0.5 millimole of vanadium per gram of support and preferably 0.2 to 0.3 millimole of these metals per gram of support. Impregnation of the abovementioned catalysts into, for example, silica is accomplished by mixing the complex and silica gel in the electron donor solvent followed by solvent removal under reduced pressure.
• the titanium based catalyst and the vanadium based catalyst can be either added separately to the polymerization reactor or dry blended together prior to addition. Premixing outside of the reactor is accomplished by physically blending the two catalysts in an inert atmosphere.
• the titanium and vanadium catalyst components can also be impregnated on a common support.
• the modifier, cocatalyst, and promoter can be added to the complexes either before or during the polymerization reaction.
• the modifier is usually introduced into the vanadium complex prior to the introduction of the vanadium complex into the mixed catalyst system.
• the cocatalyst and promoter are preferably added separately neat or as solutions in an inert solvent, such as isopentane, to the polymerization reaction at the same time as the flow of the ethylene is initiated.
• Useful molar ratios are about as follows:
• the ethylene polymerization can be conducted in the gas phase or liquid phase using conventional techniques such as fluidized bed, slurry, or solution processes.
• a continuous, fluidized bed process is preferred.
• the mixed catalyst, the cocatalyst, the promoter, the ethylene monomer, and any comonomers are continuously fed into the reactor and polyethylene product is continuously removed.
• the density of the ethylene copolymer produced may be varied over a wide range depending upon the amount of alpha-olefin comonomer added and upon the particular comonomer employed. The greater the mole percent of alpha-olefin comonomer, the lower the density.
• the fluidized bed polymerization is conducted at a temperature below the sintering temperature of the product.
• the operating temperature is generally in the range of 10°C to 115°C. Preferred operating temperatures will vary depending upon the density desired.
• High density polyethylenes of greater than 0.94 grams per cubic centimeter (g/cm3) are produced at operating temperatures of 85°C to 115°C, and preferably 90°C to 100°C.
• Low density polyethylenes ranging in density from 0.91 to 0.94 g/cm3 are preferably produced at an operating temperature of 75°C to 90°C.
• Very low density polyethylenes of less than 0.91 g/cm3 are preferably produced at an operating temperature of 10°C to 80°C. In the case of very low density polyethylenes, it is necessary to dilute the reaction mixture with a large quantity of a diluent gas in order to prevent the formation of polymer agglomerates and sustain polymerization on a continuous basis.
• the fluidized bed reactor is typically operated at pressures of up to 7 MPa (1,000 psig) and preferably 445 to 2514 KPa (50 to 350 psig).
• a chain transfer agent such as hydrogen
• hydrogen can be used to terminate the polymer chain.
• the ratio of hydrogen to ethylene will vary between 0.001 to 2.0 moles of hydrogen per mole of ethylene.
• the titanium based catalyst used in the examples is prepared according to the procedure described in United States patent 4,303,771.
• a 12 liter flask equipped with a mechanical stirrer is placed 41,8 grams (0.439 mole) of anhydrous MgCl2 and 2,5 liters of tetrahydrofuran.
• 27.7 grams (0.184 mole) TiCl4 is added over 30 minutes while stirring. During this period, the mixture is heated to 60°C to completely dissolve the material.
• Porous silica 500 grams dehydrated at 800°C is added to the solution and stirred for 15 minutes. The mixture is dried with a nitrogen purge at 60°C for 3 to 5 hours to provide a free-flowing powder having the particle size of the silica. The supported precursor is then slurried in anhydrous isopentane and treated with tri-n-hexylaluminum (modifier) using a molar ratio of 3.2 Al/Ti. The mixture is stirred at ambient temperature for 30 minutes and then dried under a purge of dry nitrogen at 65°C until the solvent is removed.
• the resulting catalyst is a free-flowing powder containing 0.23 millimole Ti per gram; a molar ratio of Mg: Ti of 3: 1; a molar ratio of Ti: Cl of 0.1: 1; a molar ratio of Al: Ti of 3.1: 1; and a molar ratio of tetrahydrofuran: Al of 5: 1.
• the vanadium based catalyst used in the examples is prepared according to the procedure described in US-A-4508842. To a flask containing 4 liters of anhydrous tetrahydrofuran are added 38 grams of VCl3 (0.242 mole). The mixture is stirred for 5 hours at 65°C under a nitrogen blanket until the VCl3 is dissolved. To this solution is added 800 grams of silica (dehydrated by heating to 600°C). Stirring is continued for 4 hours at 65°C. The flask is vented and the solution is dried at 70°C to the mud stage. The temperature is dropped to 45°C and a nitrogen purge is used until a 4 to 10 percent by weight tetrahydrofuran level is reached in the resulting precursor. The vanadium compound so produced is a free-flowing solid containing 0.3 millimole of vanadium per gram of vanadium compound. The solid is removed from the flask and stored under nitrogen.
• the titanium based catalyst has loadings of 0.22 to 0.26 millimole of titanium per gram of catalyst while the vanadium based catalyst has metal loadings of 0.17 to 0.27 millimole of vanadium per gram of catalyst.
• the titanium based catalyst and the vanadium based catalyst are both deactivated by contact with atmospheric water and oxygen so it is necessary to perform the blending operation in a dry and non-reactive gas such as nitrogen.
• a glove box containing the dry, inert gas is ideal.
• Each catalyst is separately weighed using an analytical balance and then the catalysts are dry blended together by stirring with a spatula and shaking the mixture in a sealed bottle. The mixture is visually homogeneous.
• the catalyst mixture is as air sensitive as the individual components and is stored and handled in an inert atmosphere.
• the polymerization of ethylene is conducted in a one liter autoclave equipped with a mechanical overhead stirrer and an external temperature regulating jacket.
• the autoclave is capable of providing the continuous addition of ethylene at a fixed preset pressure.
• the reactor is fitted with thermocouples to allow monitoring of the temperature of the external jacket and the internal temperature of the reactor during the polymerization.
• the ethylene feed line to the reactor is fitted with an electronic gas flow meter to allow the continuous monitoring of the ethylene flow to the reactor. All manipulation of the polymerization reaction components are conducted using airless techniques to rigorously exclude atmospheric oxygen and water.
• the reactions are conducted in a slurry of dry, deoxygenated hexane.
• the autoclave is charged with 500 milliliters of hexane and 20 milliliters of 1-hexene.
• a solution of 25 weight percent triisobutylaluminum in hexane (based on the weight of the hexane) is added by syringe to the reactor in a molar ratio of Al: Ti + V of 40: 1.
• the aluminum alkyl acts as a cocatalyst for both the titanium based catalyst and the vanadium based catalyst and, by adding the aluminum alkyl to the reactor first, it can scavenge any trace impurities.
• the addition of the catalysts to the reactor is made with the careful exclusion of air from the system.
• the promoter is then charged into the reactor as a one molar hexane solution. It is added by syringe with, as before, precautions being taken to exclude air from the reactor system.
• the reactor is sealed immediately following the addition of the last component and is then heated to 60°C.
• the reactor is then flushed with hydrogen and then pressurized with hydrogen to 108 to 170 KPa gauge (1 to 10 psig).
• Hydrogen is added to regulate the polymer molecular weight. Heating is continued to 75°C at which point the reactor is pressurized with ethylene to a pressure of 825 to 1204 KPa gauge of (105 to 160 psig).
• the ethylene flow into the reactor is monitored with a mass flowmeter and the internal and jacket temperatures of the reactor are continuously monitored during the polymerization reaction.
• the jacket temperature is regulated to maintain the internal temperature of the reactor at 85°C.
• the polymerization is conducted for 30 minutes. At that time the ethylene flow to the reactor is stopped, the reactor is vented to ambient pressure, and the jacket is flushed with cold water to bring the internal temperature to ambient as quickly as possible.
• the polymer/hexane slurry is removed from the reactor, stabilizers are added, and the solvent is allowed to evaporate overnight.
• the polymer is dried in a vacuum oven at 80°C and then weighed to determine the polymer yield.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

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• 1988
  • 1988-03-29 CN CN88101779A patent/CN1009647B/zh not_active Expired
  • 1988-03-30 AT AT88105187T patent/ATE65786T1/de not_active IP Right Cessation
  • 1988-03-30 JP JP63074847A patent/JPS63260904A/ja active Pending
  • 1988-03-30 ES ES88105187T patent/ES2023969B3/es not_active Expired - Lifetime
  • 1988-03-30 KR KR1019880003470A patent/KR880011207A/ko not_active Application Discontinuation
  • 1988-03-30 EP EP88105187A patent/EP0286001B1/en not_active Expired - Lifetime
  • 1988-03-30 DE DE8888105187T patent/DE3863954D1/de not_active Expired - Lifetime
• 1991
  • 1991-10-23 GR GR91400276T patent/GR3002967T3/el unknown

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